<template>
  <div class="pagination">

    <button :disabled="pageNo === 1" @click="$emit('getPageNo',pageNo - 1)">上一页</button>
    <button v-if="StartEndNum.start > 1"
            @click="$emit('getPageNo', 1)"
            :class="{active:pageNo === 1}">1</button>
    <button v-if="StartEndNum.start > 2">···</button>

    <!--   continues部分 -->
    <button
        v-for="(pageNum,index) in StartEndNum.end" :key="index"
        v-if="pageNum >= StartEndNum.start"
        @click="$emit('getPageNo',pageNum)"
        :class="{active:pageNo === pageNum}"
    >{{pageNum}}</button>

    <button  v-if="StartEndNum.end < totalPage -1">···</button>
    <button v-if="StartEndNum.end < totalPage "
            @click="$emit('getPageNo',totalPage)"
            :class="{active:pageNo === totalPage}"
    >
      {{ totalPage }}
    </button>

    <button :disabled=" pageNo === totalPage" @click="$emit('getPageNo',pageNo + 1)">下一页</button>

    <button style="margin-left: 30px">共 {{total}} 条</button>

  </div>
</template>

<script>
export default {
  name: "MyPagination",
  props:['pageNo','pageSize','total','continues'],
  //计算总共多少页
  computed:{
    totalPage(){
      // Math.ceil向上取整
      return Math.ceil( this.total / this.pageSize )
    },
    StartEndNum(){
      //结构数据
      const {pageNo,continues,totalPage} = this
      let start = 0
      let end = 0
      if (continues > totalPage){
        start = 1
        end = totalPage
      }else {
        start = pageNo - parseInt(continues / 2)
        end = pageNo + parseInt(continues /2 )
         if (start <= 0) {
           start = 1
           end = continues
         }
         if (end > totalPage) {
           end = totalPage
           start = totalPage - continues +1
         }

      }
      return {start,end}
    },


  }
}
</script>

<style lang="less" coped>
.pagination {
  text-align: center;

  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>